1. Field of the Invention
The present invention relates generally to the control of a supercharger for an internal combustion engine and, more particularly, to the control of an engine that is used in a marine propulsion system in a way that improves both performance and operating efficiency.
2. Description of the Prior Art
Many different systems are known which use devices to pressurize the charged air for an internal combustion engine. Some of the systems are used in conjunction with marine propulsion systems.
U.S. Pat. No. 6,378,506, which issued to Suhre et al. on Apr. 30, 2002, discloses a control system for an engine supercharging system. A bypass control valve is controlled by an engine control module as a function of manifold absolute pressure and temperature within an air intake manifold in conjunction with the barometric pressure. An air per cylinder (APC) magnitude is calculated dynamically and compared to a desired APC value which is selected as a function of engine operating parameters. The air per cylinder value is calculated as a function of the manifold absolute pressure, the cylinder swept volume, the volumetric efficiency, the ideal gas constant, and the air inlet temperature. The volumetric efficiency is selected from stored data as a function of engine speed and a ratio of manifold absolute pressure to barometric pressure.
U.S. Pat. No. 6,408,832, which issued to Christiansen on Jun. 25, 2002, discloses an outboard motor with a charge air cooler. An outboard motor is provided with an engine having a screw compressor which provides a pressurized charge for the combustion chambers of the engine. The screw compressor has first and second screw rotors arranged to rotate about vertical axes which are parallel to the axes of the crankshaft of the engine. A bypass valve regulates the flow of air through a bypass conduit extending from an outlet passage of the screw compressor to the inlet passage of the screw compressor. A charge air cooler is used in a preferred embodiment and the bypass conduit then extends between the cold side plenum of the charge air cooler and the inlet of the compressor. The charge air cooler improves the operating efficiency of the engine and avoids overheating the air as it passes through the supercharger after flowing through the bypass conduit. The bypass valve is controlled by an engine control module in order to improve power output from the engine at low engine speeds while avoiding any violation of existing limits on the power of the engine at higher engine speeds.
U.S. Pat. No. 6,405,692, which issued to Christiansen on Jun. 18, 2002, discloses an outboard motor with a screw compressor supercharger. An outboard motor is provided with an engine having a screw compressor which provides a pressurized charge for the combustion chambers of the engine. A bypass valve regulates the flow of air through the bypass conduit extending from an outlet passage of the screw compressor to the inlet passage of the screw compressor. The bypass valve is controlled by an engine control module in order to improve power output from the engine at low engine speeds while avoiding any violation of existing limits on the power of the engine at higher engine speeds.
U.S. Pat. No. 6,439,188, which issued to Davis on Aug. 27, 2002, discloses a four cycle four cylinder in-line engine with rotors of a supercharging device used as balance shafts. A four cycle four cylinder in-line internal combustion engine is provided with a housing structure that contains two shafts which rotate in opposite directions to each other and at the same rotational velocity. Pairs of counterweights are attached to the two shafts in order to provide a counterbalancing force which is generally equal to an opposite from the secondary shaking force which results from the reciprocal movement of the pistons of the engine. The first and second shafts are rotors of a supercharging device, such as a Roots blower. The rotational speed of the first and second shafts is twice that of the rotational speed of the crankshaft of the engine and the provision of counterweights on the first and second shafts balances the secondary forces caused by the reciprocal motion of the piston in the engine.
U.S. Pat. No. 5,307,783, which issued to Satoya et al. on May 3, 1994, describes a boost pressure control system for an engine. The system is equipped with a supercharger and a torque converter having a lock-up clutch, in which the boost pressure is controlled by adjusting the degree of the opening of an air bypass valve and the ON/OFF position of the supercharger in such manner that the different control characteristics of the boost pressure are selected in accordance with whether the lock-up clutch of the torque converter is turned ON or OFF. In other words, when the lock-up clutch is turned ON, the supercharger is started at a lower engine load, and the degree of the opening of the air bypass valve is set smaller, thereby enabling the lock-up operation of the torque converter under running conditions in which a higher driving torque is required and, thereby widening the operating range of the lock-up operation of the torque converter and improving the fuel economy of the vehicle.
U.S. Pat. No. 6,609,505, which issued to Janson on Aug. 26, 2003, describes a two speed supercharger drive. A supercharger system for an internal combustion engine is described. The supercharger system includes a supercharger pump that is driven by the engine via a gear box. The gear box includes two planetary gear sets and a controllable clutch. A controller selectively activates the clutch to control the transition between the two speeds to assure a smooth transition without sudden changes in torque output.
U.S. Pat. No. 6,082,340, which issued to Heimark on Jul. 4, 2000, describes a two speed supercharger. The supercharger for a motor vehicle internal combustion engine is disclosed. The engine has an air intake, a crankshaft, a rotating engine accessory and shaft and the supercharger is driven by the rotating engine accessory shaft. The supercharger consists of a rotating turbine which receives atmospheric air and provides compressed air to the engine's air intake. The rotating turbine is connected to the rotating engine accessory shaft for rotational movement. In a preferred implementation, the rotating engine accessory is the alternator. A number of gears between the alternator shaft and the turbine increases the speed of the turbine relative to the alternator shaft. The apparatus may include a two speed clutch mounted on the engine's crankshaft to provide two speeds for the alternator shaft.
U.S. Pat. No. 6,634,344, which issued to Stretch on Oct. 21, 2003, describes a controlled engagement of a supercharger drive clutch. The preferred embodiment of the present invention provides a control system and method of controlling a supercharger having an input and a pair of rotors. The method comprises providing a magnetic particle clutch having an input member, an output member and a source of magnetic flux. In the presence of a magnetic field, a magnetically reactive medium disposed between the input and output members is transformed into a torque transmitting coupling that causes the clutch to transition from a disengaged state to an engaged state. The method includes sensing a vehicle parameter and generating a signal operable to engage the clutch in response to the sensed vehicle parameter, so that the transition to the engaged state may be controlled as a function of the sensed vehicle parameter.
U.S. Pat. No. 6,375,442, which issued to Ward et al. on Apr. 23, 2002, describes a supercharger clutch system. The system has a clutch housing in which a clutch pack is disposed to transmit torque from an input, such as a pulley, to one of the timing gears. The clutch pack is disposed within a cage, having a spring seat member adjacent thereto. A set of springs biases the seat member and the clutch cage to engage the clutch pack. On the opposite side, axially, of the clutch pack there is a piston including a portion surrounding the clutch cage and engaging the seat member. The piston and the clutch housing define a pressure chamber which, when pressurized, causes movement of the piston in a direction compressing the springs and disengaging the clutch pack. With the invention, the clutch system can be operated by engine lubrication oil, while still achieving rapid engagements, wherein the rate of engagement can be modulated to suit vehicle operating conditions.
The patents described above are hereby expressly incorporated by reference in the description of the preferred embodiment of the present invention.
Although it is generally known that a clutch can be used in conjunction with a supercharger in motor vehicles, such as automobiles, marine propulsion systems operate in a manner that is significantly different than land vehicles. A marine vessel typically spends a significant portion of its operating time with the engine at idle operating speed and the transmission in neutral gear position. In addition, as the speed of the engine is increased in a marine propulsion system, the boat eventually moves to a planing position, with the operation of the marine propulsion system being much more efficient when the boat is “on plane”. When the marine propulsion system is either operating at idle speed or on plane, it does not require the full use of a supercharger. During periods of maximum acceleration and maximum requirement of thrust capability, the marine propulsion system can make efficient and advantageous use of the supercharger. It would therefore be significantly beneficial if a marine propulsion system could be provided with some way to activate and deactivate a supercharger based on the specific needs of the marine vessel.